CGSociety :: Production Focus

10 December 2012, by Paul Hellard

From visionary director Ang Lee and based on the best-selling book by Yann Martel, Life of Pi is an inspirational story of a young man who, upon surviving a shipwreck at sea, is hurtled into an epic journey of adventure and discovery.

Several studios’ VFX crews worked to make the visuals of Life of Pi a reality. The new horizons of water creation were breached to bring the full effects to the screen, as well as an immense amount of recreative animal characters, to be believed as completely real. Another area of insane effort must be recognized in the lead character actor. Suraj Sharma only accompanied his brother to the auditions to keep him company and thought he’d try out as well. Months later, he had the lead role. Never acted before, never swam before. No pressure!

Much of the production is set in the world’s largest self-generating wave tank ever designed and built for a movie production. Located on the site of a former airport in Taiwan, the tank measured 70 meters long, 30 meters wide and four meters deep, with a capacity of 1.7 million gallons, which allowed the filmmakers to generate a range of water textures.

The Life of Pi production was also shot around 200,000 square feet of studio and office space near Pondicherry’s historic Muslim Quarter in India. The production filmed on 18 locations in and around, and a crew of 600 (almost half of them locals) worked on the opening sequences of the film. Approximately 5,500 local residents were hired as background actors for the magnificent exterior scenes. The production also transformed the town’s Botanical Gardens into the fictional Pondicherry Zoo.

Overall Visual Effects Supervisor Bill Westenhofer from Rhythm & Hues, with credits from Narnia and Golden Compass had a huge job on his hands. Handing out sequences to various houses, he brought in Legacy Effects to tackle special effects for creature creation and storm work, a lot of in-country work going to Rhythm & Hues and a great many shots going to MPC. VFX Supervisor Guillaume Rocheron and VFX Producer Genevieve West led their MPC studio team, delivering over 110 shots in native stereo for the Life of Pi. This included two shots of Pi leaving India, with the view from the Tsimtsum deck. They also had to extend the set with the digital Tsimtsum, and added a CG ocean and digital matte paintings of India in the distance. MPC also did two shots for the opening credits within a zoo in India, adding hornbills around a pond, a CG lizard and Cassowaries.

The ship itself was a detailed digital double of the Tsimtsum was modelled on a 1970s era freighter and built referencing blueprints which were given to the team by production’s art department. For the sunken shots, the team comped in a CG double to underwater photography, adding underwater waves and atmospheric elements to the scene.

MPC had to deliver full digital oceans under hurricane type conditions. In total, this represented almost 12 minutes of digital storm in native 3D with waves that were 45 feet high, 820 feet long, with a lot of sprays, mist and white water everywhere.

The original photography was mostly taken in a wave tank in Taiwan or occasionally on a gimbal, the largest ever built for a movie. It was impossible, and quite dangerous, to re-create physical waves in the tank to the scale Ang wanted. This meant that in the sequences created by MPC, they had to replace the real water with CG water in every shot. In addition to the stereo element, what made their work even more challenging was Ang’s use of very long takes instead of multiple cuts. “This is absolutely fantastic to immerse the audience in the 3D footage but a lot less forgiving for us since it gives the viewer a lot of time to stare at every single detail,” explains MPC VFX Supervisor Guillaume Rocheron.

“On top of dealing with the extremely complex simulations, our main challenge was to provide Ang with a way to design and choreograph the shots, with as few constraints as possible. It is well known that this type of simulation work can be very frustrating because every change means a new simulation and every simulation gives you some slightly different results on each iteration. This can become a real problem if it starts changing timings or events that you wanted to keep and we really wanted to avoid going through those loops, especially knowing how well timed everything would have to be for the various storytelling events.”

The MPC VFX crew used Flowline for their large scale fluid simulations, so the FX and R&D teams worked with Scanline and put in place a method they called ‘Refined Sheet’. The concept was to take an existing heighfield or geometry that represents the main ocean shapes and emits a thin sheet of voxels over it to simulate interactions and water. “This represented two major advantages for us,” says Rocheron. “We would be able to use an already established wave layout to solve the water motion and most of the computing power would be used to simulate only a few feet of water depth instead of having to simulate from the bottom of the ocean which allowed us to reach the amount of details that was required for our shots.”

The MPC R&D team came up with a layout toolset based on Tessendorf deformers and Gestner waves to allow their artists to create a non simulated, geometric representation of the ocean, with a lot of controls to tweak every single component individually. They would start with a pre-established ocean template, with realistic properties in terms of wave size and timing but then they were able to add, remove, shape or keyframe individual waves.

“We really ended up treating the ocean like a character, having layout artists and animators keyframing the base layer of waves that would then drive our final simulation,” he explains. “We were able to animate that base layer, review it with Ang and Bill Westenhofer, the overall VFX Supervisor, and get the shots locked, in terms of layout and design, before we started the simulation work, which was a real game changer for us.”

“We would then sim the water surface using our Refined Sheet technique and then simulate what we call elements; based on the now simulated water surface, we would emit spray, that would then become bubbles when colliding back with the surface or mist if caught by wind and bubbles would then become foam when rising up to the surface. The amount of wind in hurricane-like conditions, meant we had to simulate a wind field above the ocean surface to fill the atmosphere with mist and rain. We ended up spending a lot of time simulating all of these since they were the key to the visual complexity of a storm. There is one shot where we simulated 1.5 billion water droplets!”

Sinking the Tsimtsum

The sinking of the cargo ship Tsimtsum was the first of the two storm sequences, and clearly the most complex with all of the various elements it involved. The MPC crew had to build a fully digital version of the Tsimtsum, which was used to either extend the deck sets or was featured in full CG when Pi gets on the lifeboat. It was based on very detailed art department blueprints and thousands of reference photos that made of tankers parked in the Vancouver Bay area.

“We also made a high resolution digital double of Pi for shots that weren’t filmable,” Rocheron adds. “We used these to transition from a live action to CG, like when Pi is on the lifeboat dropping into the ocean; where Pi is live action for the first few feet of the descent and we then transition to CG with the lifeboat hitting the water. We also used it for instances where the shots were wide enough to clearly see the lifeboat going up and down the waves since there was no way to shoot it on waves that big.”

As the story is established, we find out that Pi’s family owned a zoo back in India and took all their animals on their journey to sell them once at their destination in Canada; so when the ship starts to sink, a lot of the animals are let free, running around panicked on the decks, falling into the water and sinking with the ship. Led by Animation Supervisor Darryl Sawchuk, the team animated around 20 panicking creatures aboard the sinking Tsimtsum, including leopards, camels and rhinos, all with full muscle rigs and fur grooms.

“The zebra and the lifeboat were assets built at Rhythm & Hues,” Rocheron clarifies. “We received the model and textures and then conformed it to our pipeline with our own muscle and fur systems for the Zebra so we could put it into our shots. One of the most unique shots is when Pi plunges underwater as a massive wave crashes over him, and we see the shot of the Tsimtsum falling into the abyss from under water. It took us a few months to create the waves crashing and rolling underwater and to perfect the timing and movement of the shots. The sequence happens at night as well and the only light source were the lights of the Tsimtsum cargo ship itself. “To ensure photorealism and precision in the shaping, we used a fully raytraced solution for all of the reflections, basing our lighting mostly on area lights,” adds Rocheron.

The Storm of God

In the dramatic climax of Pi's journey, the Storm of God used pretty much the same technology for its ocean simulations as was used for the Tsimtsum sinking. Being the climax of Pi’s journey, MPC artists had to make the storm look even more fierce by making the waves bigger and more violent, with a lot of wind to increase the sense of chaos. The wind’s influence on the ocean spray generates fine spray and mist and these elements filled out frames with millions of particles. “We used our digital Pi for takeovers, impossible stunts and wide angle shots. The added dramatic element was the numerous lightning flashes, all timed to hit the water and to illuminate the scene,” says Rocheron.

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